Data from several cancer screening studies are being collected and analyzed to gain a better understanding of the impact and consequences of such screening in various population settings, and to develop new techniques for data analysis. Section staff are involved in various aspects of these studies, including design, monitoring and data analyis. The long term follow-up phase of the Health Insurance Plan of New York breast cancer screening trial was completed. Current results indicate a 30 percent reduction in breast cancer mortality at 10 years, which dropped to 25 percent at 18 years. Monitoring continues of a trial to evaluate testing for blood in the stool for the early detection of colorectal cancer. Consultation was provided regarding sample size and protocol specifications for a study to assess the sensitivity and specificity of a monoclonal antibody test for the early detection of ovarian cancer. Two occupational high risk groups are under scrutiny. In collaboration with DCE, the bladder cancer screening program at the DuPont Company is being analyzed to relate disease characteristics and outcome to urine cytology and blood tests, smoking history and chemical exposure. With DCE, and NIOSH updated follow-up data are being collected in a study of sputum cytology screening for lung cancer among uranium miners. The relationships among cytology classification, radiation exposure, smoking history, lung cancer, and mortality data will be analyzed.